This invention is related to a system for controlling fans in response to temperature, and more specifically to a system for controlling the operation of a plurality of fans associated with a cooling tower in response to the temperature of the coolant being circulated through the cooling tower.
Many industrial processes require the use of a cooling tower in which large fans are mounted on the top of a baffled structure which is designed to permit heated water from the particular industrial process to drain down from the top to the bottom of the tower while air for cooling the water is drawn in at the bottom of the structure and forced out the top by the fans. The actual cooling requirements imposed on the cooling tower facility often varies as a result of changes in the operating conditions of the particular process being cooled and changes in weather conditions. Without automatic controls for the fans, the cooling system must be manually operated. This requires an operator for continuously monitor the temperature of the coolant being pumped through the tower and to turn the fans on and off, and change the speed of the fans, as the temperature of the coolant varies. Alternatively, the fans may be operated continuously at higher than required speeds.
As can be easily seen, either alternative can be quite expensive either in terms of the wasted energy from running the fans continuously at higher than required speeds or in terms of the cost of personnel for continuously monitoring the temperature of the coolant.
It would be desirable to have a control system which automatically controls the operation of the fans in response to temperature changes of the coolant. It is also desirable that such a system be designed to be easily connected to an existing manually operated control system such that the fans can be operated either manually or automatically.